"""head."" Capitate bone The capitate bone is found in the center of the carpal bone region, colloquially known as the wrist, which is at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone (the middle finger) and forms the third carpometacarpal joint. The capitate bone is the largest of the carpal bones in the human hand. It presents, above, a rounded portion or head, which is received into the concavity formed by the scaphoid and lunate bones; a constricted portion or neck; and below this, the body. The bone is also found in"
"ulna and the metacarpus. The bones of the carpus do not belong to individual fingers (or toes in quadrupeds), whereas those of the metacarpus do. The corresponding part of the foot is the tarsus. The carpal bones allow the wrist to move and rotate vertically. The eight carpal bones may be conceptually organized as either two transverse rows, or three longitudinal columns. When considered as paired rows, each row forms an arch which is convex proximally and concave distally. On the palmar side, the carpus is concave and forms the carpal tunnel, which is covered by the flexor retinaculum. The"
"the ulnar, with two eminences; the lateral and larger is a rounded, articular eminence, termed the head of the ulna; the medial, narrower and more projecting, is a non-articular eminence, the styloid process. The head is separated from the styloid process by a depression for the attachment of the apex of the triangular articular disk, and behind, by a shallow groove for the tendon of the extensor carpi ulnaris. The ulna is a long bone. The long, narrow medullary cavity of the ulna is enclosed in a strong wall of cortical tissue which is thickest along the interosseous border and"
"Coronoid process of the ulna The Ulna's coronoid process is a triangular eminence projecting forward from the anterior proximal portion of the ulna. Its ""base"" is continuous with the body of the bone, and of considerable strength. Its ""apex"" is pointed, slightly curved upward, and in flexion of the forearm is received into the coronoid fossa of the humerus. Its ""upper surface"" is smooth, concave, and forms the lower part of the semilunar notch. Its ""antero-inferior"" surface is concave, and marked by a rough impression for the insertion of the brachialis muscle. At the junction of this surface with the"
"fracture. Olecranon The olecranon from the ""Greek"" ""olene"" meaning elbow and ""kranon"" meaning head is the large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon serves as a lever for the extensor muscles that straighten the elbow joint. It is situated at the upper (proximal) end of the ulna, one of the two bones in the forearm. When the hand faces forward (supination) the olecranon faces towards the back"
"Olecranon The olecranon from the ""Greek"" ""olene"" meaning elbow and ""kranon"" meaning head is the large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon serves as a lever for the extensor muscles that straighten the elbow joint. It is situated at the upper (proximal) end of the ulna, one of the two bones in the forearm. When the hand faces forward (supination) the olecranon faces towards the back (posteriorly)."
"of the flexor digitorum profundus muscle; descending from the eminence is a ridge which gives origin to one head of the pronator teres muscle. Frequently, the flexor pollicis longus muscle arises from the lower part of the coronoid process by a rounded bundle of muscular fibers. The coronoid process of the ulna should not be confused with the similar-sounding coracoid process of the scapula. Coronoid process of the ulna The Ulna's coronoid process is a triangular eminence projecting forward from the anterior proximal portion of the ulna. Its ""base"" is continuous with the body of the bone, and of considerable"
"coated with a thin layer of compact bone. The trabeculæ at the lower end have a more longitudinal direction. The ulna is ossified from three centers: one each for the body, the wrist end, and the elbow end, near the top of the olecranon. Ossification begins near the middle of the body of the ulna, about the eighth week of fetal life, and soon extends through the greater part of the bone. At birth, the ends are cartilaginous. About the fourth year or so, a center appears in the middle of the head, and soon extends into the ulnar styloid"
"head of the ulna. These lie on a horizontal line called the ""Hueter line"". When the elbow is flexed, they form an equilateral triangle called the ""Hueter triangle"". At the surface of the humerus where it faces the joint is the trochlea. The groove running across the trochlea is, in most people, vertical on the anterior side but spirals off on the posterior side. This results in the forearm being aligned to the upper arm during flexion, but forming an angle to the upper arm during extension — an angle known as the carrying angle. The superior radioulnar joint shares"
"against a bicycle handlebar. Ulnar canal The ulnar canal or ulnar tunnel (also known as Guyon's canal or tunnel) is a semi-rigid longitudinal canal in the wrist that allows passage of the ulnar artery and ulnar nerve into the hand. The roof of the canal is made up of the superficial palmar carpal ligament, while the deeper flexor retinaculum and hypothenar muscles comprise the floor. The space is medially bounded by the pisiform and pisohamate ligament more proximally, and laterally bounded by the hook of the hamate more distally. It is approximately 4 cm long, beginning proximally at the transverse"
"Ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspect of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery. It is palpable on the anterior and medial aspect of the wrist. Along its course, it is accompanied by a similarly named vein or veins, the ulnar vein or ulnar veins. The ulnar artery, the larger of the two terminal branches of the brachial, begins a little below the bend of the elbow in the cubital fossa,"
"the humerus. Both the ulna and the radius are relatively straight bones. The top of the ulna bears three ""prongs"", namely the olecranon process and two additional triangular flanges. Meanwhile, the radius bears a flattened inner surface at the top end, and a distinct platform on the inner surface at the bottom end, both for articulating with the ulna. The hand has five digits. Among the metacarpal bones of the hand, the second is curved, the third is straight, and the fourth is strongly curved. Like ""Iguanodon"", ""Probactrosaurus"", and other basal iguanodonts, the claw on the first digit is distinctively"
"Humeroulnar joint The humeroulnar joint (ulnohumeral or trochlear joint), is part of the elbow-joint. It is composed of two bones, the humerus and ulna, and is the junction between the trochlear notch of ulna and the trochlea of humerus. It is classified as a simple hinge-joint, which allows for movements of flexion, extension and circumduction. Owing to the obliquity of the trochlea of the humerus, this movement does not take place in the antero-posterior plane of the body of the humerus. When the forearm is extended and supinated, the axis of the arm and forearm are not in the same"
"from the distal third of the dorsal part of the body of ulna. The APL, EPB, EPL, and EI all have an additional origin at the interosseus membrane. The ECRL and ECRB, (with the brachioradialis) form the lateral compartment. Their muscle fibers end at the upper third and the mid forearm respectively, continuing as flat tendons along the lateral border of the radius, beneath the APL and EPB. They then pass beneath the extensor retinaculum and dorsal carpal ligament, where they lie in a groove on the back of the radius, immediately behind the styloid process, and continue into the"
"Ulnar styloid process The styloid process of the ulna is found at distal end of the forearm, and projects from the medial and back part of the bone; it descends a little lower than the head, and its rounded end affords attachment to the ulnar collateral ligament of the wrist. The head is separated from the styloid process by a depression for the attachment of the apex of the triangular articular disk, and behind, by a shallow groove for the tendon of the extensor carpi ulnaris muscle. Ulnar styloid fractures seldom require treatment when they occur in association with a"
"Humerus The humerus (, plural: ""humeri"") is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its"
"concurrent fracture of the distal radius, the ulna, or can be isolated. A classification system has been proposed by Estaminet and colleagues. Estaminet classified injuries of the distal radioulnar articulation into four categories with two subclasses: purely ligamentous (subclass A) and those with associated boney injury (subclass B). Distal radioulnar articulation The distal radioulnar articulation (inferior radioulnar joint) is a joint between the two bones in the forearm; the radius and ulna. It is one of two joints between the radius and ulna, the other being the proximal radioulnar articulation. The distal radioulnar articulation is the one of the two"
"flexor muscles are more massive than the extensors, because they work against gravity and act as anti-gravity muscles. The ulnar nerve also runs the length of the forearm. The radial and ulnar arteries and their branches supply the blood to the forearm. These usually run on the anterior face of the radius and ulna down the whole forearm. The main superficial veins of the forearm are the cephalic, median antebrachial and the basilic vein. These veins can be used for cannularisation or venipuncture, although the cubital fossa is a preferred site for getting blood. ""(See separate nerve articles for details"
"Ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body (meaning unprotected by muscle or bone), so injury is common. This nerve is directly connected to the little finger, and the adjacent half of the ring finger, innervating the palmar aspect of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds. This nerve can cause an electric shock-like sensation"
"epicondyle of the humerus. Extension in the humeroulnar joint is produced by the triceps brachii and anconeus muscle, with a tiny contribution from the muscles arising from the lateral epicondyle of the humerus, such as the extensor digitorum muscle. Humeroulnar joint The humeroulnar joint (ulnohumeral or trochlear joint), is part of the elbow-joint. It is composed of two bones, the humerus and ulna, and is the junction between the trochlear notch of ulna and the trochlea of humerus. It is classified as a simple hinge-joint, which allows for movements of flexion, extension and circumduction. Owing to the obliquity of the"
"Ulnar canal The ulnar canal or ulnar tunnel (also known as Guyon's canal or tunnel) is a semi-rigid longitudinal canal in the wrist that allows passage of the ulnar artery and ulnar nerve into the hand. The roof of the canal is made up of the superficial palmar carpal ligament, while the deeper flexor retinaculum and hypothenar muscles comprise the floor. The space is medially bounded by the pisiform and pisohamate ligament more proximally, and laterally bounded by the hook of the hamate more distally. It is approximately 4 cm long, beginning proximally at the transverse carpal ligament and ending"
"Scapula In anatomy, the scapula (plural scapulae or scapulas), also known as shoulder bone, shoulder blade, wing bone or blade bone, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones the scapulae are paired, with the scapula on either side of the body being roughly a mirror image of the other. The name derives from early Roman times when it was thought that the bone resembled a trowel or small shovel. In compound terms, the prefix omo- is used for the shoulder blade in Latin medical terminology. The prefix is"
"to the pisiform and hook of hamate. The narrowest section of the tunnel is located a centimetre beyond the mid-line of the distal row of carpal bones where the sectional area is limited to 1.6 cm. The tendons of the flexor digitorum superficialis and profundus pass through a common ulnar sheath, while the tendon of the flexor pollicis longus passes through a separate radial sheath. The mesotendon shared by these tendons is attached to the radial and palmar walls of the carpal tunnel. Superficial to the carpal tunnel and the flexor retinaculum, the ulnar artery and ulnar nerve pass through"
"occupies the anterior, lower, and posterior parts of the extremity. The grooved portion of the articular surface fits accurately within the semilunar notch of the ulna; it is broader and deeper on the posterior than on the anterior aspect of the bone, and is inclined obliquely downward and forward toward the medial side. Above the front part of the trochlea is a small depression, the coronoid fossa, which receives the coronoid process of the ulna during flexion of the forearm. Above the back part of the trochlea is a deep triangular depression, the olecranon fossa, in which the summit of"
"by the addition of some transverse fibers. The extensor retinaculum is attached laterally to the lateral margin of the radius. However, it is not attached to the ulna, as the distance between these two bones varies with supination and pronation of the forearm. Instead the medial attachment is to the most medial of the carpal bones, the triquetrum (or triquetral bone) and pisiformis (or pisiform bone). The retinaculum is also attached in its passage across the wrist, to the ridges on the dorsal surface of the radius. Structurally, the retinaculum consists of three layers. The deepest layer, the gliding layer,"
"of that muscle, in relation with the ulnar nerve, it supplies the neighboring muscles and the elbow-joint, and anastomoses with the superior and inferior ulnar collateral arteries and the interosseous recurrent arteries. Posterior ulnar recurrent artery The posterior ulnar recurrent artery is an artery in the forearm. It is one of two recurrent arteries that arises from the ulnar artery, the other being the anterior ulnar recurrent artery. The posterior ulnar recurrent artery being much larger than the anterior and also arises somewhat lower than it. It passes backward and medialward on the flexor digitorum profundus, behind the flexor digitorum"
"Inferior ulnar collateral artery The inferior ulnar collateral artery (anastomotica magna artery) is a artery in the arm. It arises about 5 cm. above the elbow from the brachial artery. It passes medialward upon the Brachialis, and piercing the medial intermuscular septum, winds around the back of the humerus between the Triceps brachii and the bone, forming, by its junction with the profunda brachii, an arch above the olecranon fossa. As the vessel lies on the brachialis, it gives off branches which ascend to join the superior ulnar collateral: others descend in front of the medial epicondyle, to anastomose with"
"a pronounced keel on the trochlear notch on the ulna, which is more flattened in, for example, humans and gorillas. In knuckle-walkers, on the other hand, the elbow has to deal with large vertical loads passing through extended forearms and the joint is therefore more expanded to provide larger articular surfaces perpendicular to those forces. Derived traits in catarrhini (apes and Old World monkeys) elbows include the loss of the entepicondylar foramen (a hole in the distal humerus), a non-translatory (rotation-only) humeroulnar joint, and a more robust ulna with a shortened trochlear notch. The proximal radioulnar joint is similarly derived"
"projection, the postglenoid process, which is similar in length to that of ""Sinornithoides"" but longer than that of ""Sinovenator"". Unlike ""Sinornithoides"", the furcula is robust, flattened, and U-shaped like that of ""Mei"". Like derived troodontids, the slender upper arm bone is about 70% of the length of the thighbone. On the upper arm bone, however, the deltopectoral crest, the bone plate serving for muscle attachment, is short compared to ""Linhevenator"" and other derived troodontids, occupying only 20% of the shaft length. The ulna, the main lower arm bone, which is 88% of the length of the upper arm, exhibits a"
"back of the hand and arm. This confusion can arise because the forearm can pronate and supinate. Similarly, in the forearm, for clarity, the sides are named after the bones. Structures closer to the radius are radial, structures closer to the ulna are ulnar, and structures relating to both bones are referred to as radioulnar. Similarly, in the lower leg, structures near the tibia (shinbone) are tibial and structures near the fibula are fibular (or peroneal). Most terms of anatomical location are relative to linear motion (translation) along the X- Y- and Z-axes, but there are other degrees of freedom"
"ulna as they reach to shallow depressions on the humerus; i.e. the head of radius being pressed against the radial fossa and the coronoid process being pressed against the coronoid fossa. Passive flexion is further limited by tension in the posterior capsular ligament and in triceps brachii. A small accessory muscle, so called epitrochleoanconeus muscle, may be found on the medial aspect of the elbow running from the medial epicondyle to the olecranon. Elbow extension is simply bringing the forearm back to anatomical position. This action is performed by triceps brachii with a negligible assistance from anconeus. Triceps originates with"
"The ulna of the lower arm is long, with a minimum length equalling 76% of the humerus, upper arm bone, length. The surface on the radius contacting the ulna is limited in size and relatively smooth. The joint surface at the underside of the radius is bevelled relative to the shaft, at an angle of about 15°. The outer edge of the top surface of the shinbone forms a pinched process, behind the cnemial crest at the front. Combined, there are thirteen autapomorphies present in ""Galeamopus"", exactly the minimum the study used as a criterion to distinguish separate genera. The"
"animal is normally borne by both the sole and the edge of the hoof wall. Hooves grow continuously, and are constantly worn down by use. In most modern ungulates, the radius and ulna are fused along the length of the forelimb; early ungulates, such as the arctocyonids, did not share this unique skeletal structure. The fusion of the radius and ulna prevents an ungulate from rotating its forelimb. Since this skeletal structure has no specific function in ungulates, it is considered a homologous characteristic that ungulates share with other mammals. This trait would have been passed down from a common"